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The concept of any CMS including XOOPS is that your site has functionality but your page is blank until you fill it with bits and pieces of functionality that highlight the content in your various modules of functionality. Think of the home page like the front of an interactive newspaper. It's not all on the home page, rather teasers to get you to visit sections of interactive content. Blocks are the way to display these teasers.
There is also a method to allow you to specify a specific module to be the start page, but I only recommend this on single function sites. Most sites aren't, but I run across them. Even if they were, though, I think XOOPS (and any CMS) is still better off using a block as appropriate.
BTW, there is also now a system block/template for the home page that will show whatever you put in there if it's not blank.